The great saphenous vein (GSV) often presents partial hypoplasty. The present study elucidates the frequency of hypoplasty and the positional tendency with which GSVs present hypoplasty. GSVs taken from 41 lower limbs of embalmed cadavers were divided into four types according to the positions of their hypoplastic parts. They are, Type 1: GSVs that don’t present hypoplasty; Type 2a: GSVs in which hypoplasty is located in the upper thigh; Type 2b: GSVs in which hypoplasty is located in the lower thigh; Type 2c: GSVs in which hypoplasty extends to both the upper thigh and lower thigh. The numbers of the specimens of these anatomical types were counted. For types presenting with partial hypoplasty, length of the hypoplastic parts and the distances between the hypoplastic parts and the knee were evaluated. The anatomical types occurred in descending frequency as follows: Type 2b (65.8%), Type 1 (24.3%), Type 2a (7.3%), and Type 2c (2.4%). The average length of hypoplastic parts was 10±3.3SD cm for Type 2b and 5.8±2.3SD cm for Type 2a. The average distance of the hypoplastic parts from the knee was 10.0±5.2SD cm for Type 2b and 10.5±6.5SD cm for Type 2a. A majority (75.6%) of GSVs present partial hypoplasty. For successful performance of bypass surgery for critically ischemic limbs, care should be taken not to include hypoplastic parts in conduits. The findings of the present study are useful to avoid hypoplastic parts when creating bypass conduits.